Average route winds

[Vulcan 14]

I think I had a problem with average route winds in build 163.Could Damian or Jim comment on the attched screen shot please?It looks to me as though the winds are NW to NE yet the average route wind is shown as 166 degrees which seems to be 180 degrees out?BTW thanks for the latest build guys.http://forums.avsim.net/user_files/105414.jpg

[JSkorna 137]

Hi,I came out with 171 by hand.You have 10 SWYou have 4 NWYou have 10 NEYou are looking at the WDIR right?Hope this helps,JimActiveSky Supporthttp://www.hifisim.com/images/as2004proudsupporter.jpg

[Guest hlm65]

Hi Jim,I don't know how does AS calculate the average wind, but if it's calculated taking into account direction AND speed, the correct value for the above flight plan should be 305/77 (that is the computed value if you do a sum that calculates a "weight" for each value multiplying direction x speed, effectively giving you a vectorial sum).If it takes into account only direction, the correct value should be 352 as for direction and still 77 kts as for speed.171 or 166 seem to me both wrong.

[Vulcan 14]

>You are looking at the WDIR right?

[netshadoe 144]

I think it is a problem of the program not knowing where the winds are. The average is the sum of all the numbers divided by the amount of numbers added up (25 I think). Adding up the directions I got 4146 and divided that by 25 to get 165.84 or 166 which is in the average.Now The problem I am talking about is that the program does not realize that the winds are swinging from NW-N-NE as we see in increasing direction values. Extrapolating the teens and twenties numbers with 360 added (there were 11 of them, so add 11x360 to the 4146 added above to get 8106) and divided by 25 I got an average wind component of 324.24, which should be the proper answer.Instead, the program assumes that the winds went from NW-W-SW-S-SE-E-NE hence the average of 166.I guess what I'm trying to point out is that the wind can swing both directions.I guess it another bug that might be able to be fixed by the gurus from hifi!!!DevinCYOW

[Big_Duke 11]

It's a simple arithmetic average - add up all the WDIR values and divide by the total number of entries. Works out to to about 165.86, rounded up to 166. The difficulty is that you have a severe wind direction shift mid-way through the route; the values don't "cancel" each other out, rather they "average" out to 166 which won't help much in FMC calculations unless you enter the average for the first series of the generally westerly winds, then update with the average of the generally easterly winds mid-way through the flight.Jerry PostKORF

[Vulcan 14]

Thanks for all the replies and math calculations but I still think there is a problem especially if wind speed is taken into account, less so if speed for each direction is ignored.It is many decades since I had to use vector diagrams so I had to go looking on the net on how to produce them.I started by breaking the reported values down into quadrants and averaging the direction and speed, the results I got were231 degrees at 68.6kts332 degrees at 26kts24 degrees at 90kts.If you do a head-to-tail vector diagram of those values you should end up with a wind direction of 350-020 degrees, not 160 degrees.I cannot be more accurate because I only sketched the vectors, even ignoring the wind speed and making the vectors the same length (same wind speed) you still end up with a Northerly wind not a Southerly one.If anyone needs help with vector diagrams, as I did, try this link.http://www.glenbrook.k12.il.us/gbssci/phys...tors/u3l1b.htmlI don't wish to labour the point and I leave it up to Damian and team if they wish to look at the problem but I will now look more closely at those average winds before entering them in a fuel planner for head or tail wind.Rgds

[JSkorna 137]

Hi All,Thanks to everyone for their ideas! It's good to see everyone's thoughts without bashing and name calling as can happen in other forums. I used the simple math average, but must have punched a number in wrong. There is only one way to know for sure, so I'll point Damian to this thread. Maybe it's a bug or maybe it's a simplestic calculation!Hope this helps,JimActiveSky Supporthttp://www.hifisim.com/images/as2004proudsupporter.jpg

[Damian Clark 948]

Hi all :)It's a bug in the calculations... Will get this fixed ASAP! Thanks for all the feedback!Best,

[JSkorna 137]

No All.... I didn't get a chance to point this out!!Hope this helps,JimActiveSky Supporthttp://www.hifisim.com/images/as2004proudsupporter.jpg

[Vulcan 14]

Jim,>It's good to see everyone's thoughts without bashing and name calling as can happen in other forums.

[Guest hlm65]

Hi Damian,in the fix you plan to implement the vectorial sum ? This will give a much more correct result !Thanks a lot.Enrico.

[Damian Clark 948]

Hi Enrico,The fix was a simple correction of the code, the wrong variable was called in the summing of the "itemized" directions. If workdirection > 180 then workdirection = workdirection - 360. Unfortunately before it was if workdirection > 180 then = - 360. Thus it was never properly making the >180 values negative and thus the incorrect calculation when the wind swings around the 0deg mark.All fixed! B173 available at top of forum!Thanks again all!

[Vulcan 14]

Many thanks for the fix Damian for what was probably an obscure bug.

[Damian Clark 948]

You're very welcome - And many thanks for helping us isolate it!!!